System and Method for a Switchable Capacitance

A method of operating a switchable capacitance circuit, the method comprising:

• increasing a load capacitance of the switchable capacitance circuit comprising switching-on at least one of a plurality of capacitance-switch cells, wherein
• each of the plurality of capacitance-switch cells comprises
• a capacitance circuit having a capacitance between a first terminal and a second terminal of the capacitance circuit, and
• a semiconductor switching circuit comprising
• a first terminal coupled to the first terminal of the capacitance circuit,
• a plurality of series connected radio-frequency (RF) switch cells comprising a load path and a common node, wherein each of the plurality of series connected RF switch cells comprises a switch transistor and a gate resistor having a first end coupled to a gate of the switch transistor and a second end coupled to the common node, and
• a resistance circuit having a first end coupled to the common node and a second end coupled to a control node, wherein the resistance circuit comprises a resistance between the first end and the second end,
• switching-on comprises activating the semiconductor switching circuit of the at least one of the plurality of capacitance-switch cells;
• and
• decreasing the load capacitance of the switchable capacitance circuit comprising switching-off the at least of the plurality of capacitance-switch cells, wherein switching-off comprises deactivating the semiconductor switching circuit of the at least one of the plurality of capacitance-switch cells.

A tunable radio-frequency (RF) circuit comprising:

• a semiconductor substrate;
• and
• a plurality of capacitance-switch cells disposed on the semiconductor substrate, wherein each capacitance-switch cell comprises:
• a capacitor coupled between a first terminal and a second terminal, and
• a semiconductor switching circuit comprising
• a first terminal coupled to the first terminal of the capacitor,
• a plurality of series connected radio-frequency (RF) switch cells comprising a load path and a common node, wherein each of the plurality of series connected RF switch cells comprises a switch transistor and a gate resistor having a first end coupled to a gate of the switch transistor and a second end coupled to the common node, and
• a common resistor having a first end coupled to the common node and a second end coupled to a control node.